Field of the Invention
The present invention relates to examined-portion information acquisition apparatuses. Specifically, the present invention relates to, for example, photoacoustic apparatuses for measuring an acoustic wave produced by the photoacoustic effect. As photoacoustic apparatuses, there are photoacoustic apparatuses for use in observation of a chest portion of a living body, etc.
Description of the Related Art
Recently, the development of photoacoustic tomography (PAT) diagnosis apparatuses that utilize the photoacoustic effect has been promoted. These apparatuses radiate illumination light (near-infrared light) from a pulsed Nd:YAG laser light source onto a target object; receive, using a two-dimensional or three-dimensional array of transducers, an acoustic wave produced by the photoacoustic effect inside the target object upon irradiation, and generate and display an image. A specific procedure of a photoacoustic-effect-based imaging method is as follows:
(1) The two-dimensional array of transducers is positioned with respect to the surface of an examined object, and single-pulse electromagnetic energy is radiated onto an examined portion;
(2) Signals received by the individual transducers are sampled and stored from when the electromagnetic energy has been radiated;
(3) For each point Ps inside the examined portion to be visualized, delay times taken by an acoustic wave to reach positions Pt of the individual transducers i from the point Ps are calculated, and signals of the individual transducers obtained at timings corresponding to the calculated delay times are added together, and the resulting sum is used as a pixel value for the point Ps; and(4) Step (3) is repeated for each point Ps to be imaged.
As an example of photoacoustic apparatuses according to the related art, Japanese Patent No. 4341987 discloses an apparatus that performs a photoacoustic measurement by causing a receiver including spirally arranged transducers to perform a scan in a circular motion.
In order to receive acoustic waves produced at two examined portions (e.g., right and left breasts) by using the apparatus disclosed in Japanese Patent No. 4341987, an examined person needs to change the examined portion. For example, in the case where acoustic waves produced at the right and left breasts are received, a motion to change the breast while in a prone position imposes a physical load on the examined person, and increases the time required for reception.